Loss of Heterozygosity for Kras(G12D) Promotes Malignant Phenotype of Pancreatic Ductal Adenocarcinoma by Activating HIF-2 alpha-c-Myc-Regulated Glutamine Metabolism

Loss of heterozygosity (LOH) for KRAS, in which a wild-type KRAS allele is progressively lost, promotes invasive and migratory abilities of pancreatic ductal adenocarcinoma (PDAC) cells and tissues. Moreover, the occurrence of Kras(G12D)-LOH activates nonclassical glutamine metabolism, which is related to the malignant behavior of PDAC cells. Herein, we aim to demonstrate the regulatory link between hypoxia-inducible factor-2 alpha (HIF-2 alpha) and glutamine metabolism that mediates malignant phenotypes in Kras(G12D)-LOH PDAC cells. HIF-2 alpha-shRNA knockdown lentivirus transfection and metabolite analysis were performed in Kras(G12D)-LOH and Kras(G12D) cell lines, respectively. Cell proliferation, migration, and invasion were examined using Cell Counting Kit-8, colony formation, and Transwell assays. Cell cycle phase and apoptosis were determined using flow cytometry. Western blotting and real-time quantitative PCR were also performed. Additionally, a subcutaneous xenograft mouse model was established. LOH stimulated HIF-2 alpha activity and transactivated c-Myc, which has a central regulatory effect on glutamine metabolism independent of hypoxia. Meanwhile, HIF-2 alpha silencing repressed Kras(G12D)-LOH PDAC cell proliferation, invasion, and migration. HIF-2 alpha knockdown inhibited glutamine uptake and GOT1 expression via a c-Myc-dependent pathway. Collectively, Kras(G12D)-LOH can activate HIF-2 alpha to regulate c-Myc-mediated glutamine metabolism and promote malignant phenotypes. Moreover, targeting HIF-2 alpha-c-Myc regulated nonclassical glutamine metabolism, providing a new therapeutic perspective for Kras(G12D)-LOH PDAC.

Automated summary

This study investigates the regulatory link between hypoxia-inducible factor-2 alpha (HIF-2 alpha) and glutamine metabolism in pancreatic ductal adenocarcinoma (PDAC) cells with KRAS loss of heterozygosity (LOH). The results demonstrate that KRAS LOH stimulates HIF-2 alpha activity, which activates c-Myc and leads to nonclassical glutamine metabolism. Targeting HIF-2 alpha-c-Myc regulated glutamine metabolism may provide a new therapeutic approach for KRAS LOH PDAC.